There are known in the art fasteners which function as an internally threaded nut with the benefit of being captivated to an element of the application such as a sheet or panel. A typical configuration of a fastener captivated in a sheet is a simple threaded nut with female threads which utilizes a hex shape body to allow turning by a tool to turn the nut. Such a fastener is shown for example in U.S. Pat. No. 6,486,402 issued to Harger et al. which discloses a loosely-held rivet type nut rotatably secured to a strap. The nut is attached to the strap by a staking shaft which extends from the backside of the nut. The shaft is first inserted through an aperture in the strap and then flared on the opposite side of the strap to a diameter greater than the aperture. This provides a loose riveting of the nut which permits it to be rotatable while being secured to the strap.
Simple, one-piece fasteners of this type provide the advantages and convenience of captivation, however there are problems. Spacing between the captivation element such as a sheet or panel and the attached part cannot be easily or accurately controlled and many applications have the need for spacing to be predetermined to accommodate a minimum clearance between the components to be joined. In larger applications, tolerance stack-up can also present a problem, especially in an environment subject to significant changes in temperature where a desired spacing may be lost due to the relative variations in the size of the parts because of their different coefficients of expansion. An accurately predetermined spacing may also be needed where a gasket is employed between the joined parts. Yet another problem is the force limitation of the flare or rivet on the backside of the nut because that portion of the material may be too compliant to sufficiently counteract high attachment forces against an attached component. There is therefore a need in the art for a captive nut assembly to overcome these problems.